/*
 * @(#)HeaderParser.java	1.16 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.  
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER  
 *   
 * This program is free software; you can redistribute it and/or  
 * modify it under the terms of the GNU General Public License version  
 * 2 only, as published by the Free Software Foundation.   
 *   
 * This program is distributed in the hope that it will be useful, but  
 * WITHOUT ANY WARRANTY; without even the implied warranty of  
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU  
 * General Public License version 2 for more details (a copy is  
 * included at /legal/license.txt).   
 *   
 * You should have received a copy of the GNU General Public License  
 * version 2 along with this work; if not, write to the Free Software  
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  
 * 02110-1301 USA   
 *   
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa  
 * Clara, CA 95054 or visit www.sun.com if you need additional  
 * information or have any questions. 
 *
 */

package sun.net.www;

import java.util.Iterator;

/* This is useful for parsing multi-part HTTP/RFC822 headers
 * sensibly:
 * From a String like: 'timeout=15, max=5'
 * create an array of Strings:
 * { {"timeout", "15"},
 *   {"max", "5"}
 * }
 * From one like: 'Basic Realm="FuzzFace" Foo="Biz Bar Baz"'
 * create one like (no quotes in literal):
 * { {"basic", null},
 *   {"realm", "FuzzFace"}
 *   {"foo", "Biz Bar Baz"}
 * }
 * keys are converted to lower case, vals are left as is....
 *
 * @version 1.9, 11/09/00
 * @author Dave Brown
 */ 


public class HeaderParser {

    /* table of key/val pairs */
    String raw;
    String[][] tab;
    int nkeys;
    int asize = 10; // initial size of array is 10
    
    public HeaderParser(String raw) {
	this.raw = raw;
	tab = new String[asize][2];
	parse();
    }

    private HeaderParser () {
    }

    /**
     * create a new HeaderParser from this, whose keys (and corresponding values)
     * range from "start" to "end-1" 
     */
    public HeaderParser subsequence (int start, int end) {
	if (start == 0 && end == nkeys) {
	    return this;
	}
	if (start < 0 || start >= end || end > nkeys)
	    throw new IllegalArgumentException ("invalid start or end");
	HeaderParser n = new HeaderParser ();
	n.tab = new String [asize][2];
	n.asize = asize;
	System.arraycopy (tab, start, n.tab, 0, (end-start));
	n.nkeys= (end-start);
	return n;
    }
	
    private void parse() {
	
	if (raw != null) {
	    raw = raw.trim();
	    char[] ca = raw.toCharArray();
	    int beg = 0, end = 0, i = 0;
	    boolean inKey = true;
	    boolean inQuote = false;
	    int len = ca.length;
	    while (end < len) {
		char c = ca[end];
		if ((c == '=') && !inQuote) { // end of a key
		    tab[i][0] = new String(ca, beg, end-beg).toLowerCase();
		    inKey = false;
		    end++;
		    beg = end;
		} else if (c == '\"') {
		    if (inQuote) {
			tab[i++][1]= new String(ca, beg, end-beg);
			inQuote=false;
			do {
			    end++;
			} while (end < len && (ca[end] == ' ' || ca[end] == ','));
			inKey=true;
			beg=end;
		    } else {
			inQuote=true;
			end++;
			beg=end;
		    }
		} else if (c == ' ' || c == ',') { // end key/val, of whatever we're in
		    if (inQuote) {
			end++;
			continue;
		    } else if (inKey) {
			tab[i++][0] = (new String(ca, beg, end-beg)).toLowerCase();
		    } else {
			tab[i++][1] = (new String(ca, beg, end-beg));
		    }
		    while (end < len && (ca[end] == ' ' || ca[end] == ',')) {
			end++;
		    }
		    inKey = true;
		    beg = end;
		} else {
		    end++;
		}
		if (i == asize) { 
		    asize = asize * 2;
		    String[][] ntab = new String[asize][2];
		    System.arraycopy (tab, 0, ntab, 0, tab.length);
		    tab = ntab;
		}
	    } 
	    // get last key/val, if any
	    if (--end > beg) {
		if (!inKey) {
		    if (ca[end] == '\"') {
			tab[i++][1] = (new String(ca, beg, end-beg));
		    } else {
			tab[i++][1] = (new String(ca, beg, end-beg+1));
		    }
		} else {
		    tab[i++][0] = (new String(ca, beg, end-beg+1)).toLowerCase();
		}
	    } else if (end == beg) {
		if (!inKey) {
		    if (ca[end] == '\"') {
			tab[i++][1] = String.valueOf(ca[end-1]);
		    } else {
			tab[i++][1] = String.valueOf(ca[end]);
		    }
		} else {
		    tab[i++][0] = String.valueOf(ca[end]).toLowerCase();
		}
	    } 
	    nkeys=i;
	}
	
    }

    public String findKey(int i) {
	if (i < 0 || i > asize)
	    return null;
	return tab[i][0];
    }

    public String findValue(int i) {
	if (i < 0 || i > asize)
	    return null;
	return tab[i][1];
    }

    public String findValue(String key) {
	return findValue(key, null);
    }

    public String findValue(String k, String Default) {
	if (k == null)
	    return Default;
	k = k.toLowerCase();
	for (int i = 0; i < asize; ++i) {
	    if (tab[i][0] == null) {
		return Default;
	    } else if (k.equals(tab[i][0])) {
		return tab[i][1];
	    }
	}
	return Default;
    }

    class ParserIterator implements Iterator {
	int index;
	boolean returnsValue; // or key

	ParserIterator (boolean returnValue) {
	    returnsValue = returnValue;
	}
	public boolean hasNext () {
	    return index<nkeys;
	}
	public Object next () {
	    return tab[index++][returnsValue?1:0];
	}
	public void remove () {
	    throw new UnsupportedOperationException ("remove not supported");
	}
    }

    public Iterator keys () {
	return new ParserIterator (false);
    }

    public Iterator values () {
	return new ParserIterator (true);
    }

    public String toString () {
	Iterator k = keys();
	StringBuffer sbuf = new StringBuffer();
	sbuf.append ("{size="+asize+" nkeys="+nkeys+" ");
	for (int i=0; k.hasNext(); i++) {
	    String key = (String)k.next();
	    String val = findValue (i);
	    if (val != null && "".equals (val)) {
		val = null;
	    }
	    sbuf.append (" {"+key+(val==null?"":","+val)+"}");
	    if (k.hasNext()) {
		sbuf.append (",");
	    }
	}
	sbuf.append (" }");
	return new String (sbuf);
    }

    public int findInt(String k, int Default) {
	try {
	    return Integer.parseInt(findValue(k, String.valueOf(Default)));
	} catch (Throwable t) {
	    return Default;
	}
    }
    /*
    public static void main(String[] a) throws Exception {
	System.out.print("enter line to parse> ");
	System.out.flush();
	DataInputStream dis = new DataInputStream(System.in);
	String line = dis.readLine();
	HeaderParser p = new HeaderParser(line);
	for (int i = 0; i < asize; ++i) {
	    if (p.findKey(i) == null) break;
	    String v = p.findValue(i);
	    System.out.println(i + ") " +p.findKey(i) + "="+v);
	}
	System.out.println("Done!");

    }
    */
}
